Pyrotechnic devices

ABSTRACT

A signal device operable under water and released to rise to and burn at the surface, has a casing open at one end, signal composition therein, igniting means therefor, and plug means for inhibiting passage under water between the open end and the signal composition which permits the escape of combustion products when the device is initially lighted but which is expelled or consumed when the combustion gases are generated at a higher rate. A fuse imparts delay between operation of the igniting means and ignition of the signal composition.

United States Patent 1191 1111 3,762,327

Murray et al. 1 1 Oct. 2, 1973 1 PYROTECHNIC DEVICES 1102,47? 9/1963Stefan et 111 .1 102/376 3,566.791 3/1971 Lohkampum 102/32 [75] Dudley3,051,085 8/1962 Finkelstein 6. 102 37 near sallsbury; Gordon Wilfred2,119,697 6/1938 Anderson l02/37.8 ux Curtis, Bulford Village, both ofEngland Primary Examiner-Robcrt F. Stahl [73] Assignee: Pains-WessexLimited, Wiltshire Attorney-Hall and Houghton England [22] Filed: May 4,1970 [57] ABSTRACT [21 Appl. No.: 34,306 A signal device operable underwater and released to rise to and burn at the surface, has a casing openat one end, signal composition therein, igniting means there 2; 25 Q223; 4 for, and plug means for inhibiting passage under water I 0 b/'between the open end and the signal composition which permits the escapeof combustion products when th l'ht h' l References Cited 6 devlce 1s1n1t1ally 1g ed but WhlC 1s expe led or consumed when the combustiongases are generated at UNITED STATES PATENTS a higher rate. A fuseimparts delay between operation 2920.560 1/1960 Clauser et a1 102/37.8 Xof the igniting means and ignition of the signal compo- 3,29s.311 1/1967Catlin 102/3778 x 51110 v{103,883 9/1963 Ormanns... l02/39 2,075,8134/1937 King 102/37.8 X 10 Claims, 2 Drawing Figures PATENTEDBET 2 msTUDLi) 6. M m,

6 P /v M/ (410175 INVENTOR 5 BY M 2am ATTORNEY PYROTECHNIC DlEVTCES Thisinvention relates to pyrotechnic signal devices, and especially topyrotechnic signal devices suitable for being operated and released fromunder water.

The invention provides a pyrotechnic signal device which comprises acasing, one end of which is open, a mass of signal composition containedin the casing, means for igniting the signal composition, and meansarranged to plug the casing between the composition and the open end ofthe casing, the plug means preventing or impeding the passage of waterfrom the open end of the casing to the composition, and being arrangedto be expelled from the casing or destroyed by gases of combustion whenthe pressure of these gases reaches a sufficiently high value, to allowfree escape of the combustion products.

The provision of such plug means in a signal device enables devices tobe constructed which can be operated under water and released, and whichwill rise to the surface and burn at the surface. The plug meansprevents the amount of water reaching the composition from being greatenough to extinguish the combustion before the composition has beenproperly ignited. When the plug means has been expelled from the easingor destroyed, the combustion gases from the burning composition escapefrom the open end of the casing and the velocity of the combustion gasesfrom the composition is such that the quantity of water which can enterthe casing is insufficient to extinguish the burning of the composition.

Advantageously, at least a portion of the plug means is formed of awater-absorbent material. Advantageously, at least a portion of the plugmeans that is adjacent to the wall of the casing is formed of acompressible material, enabling a good fit to be achieved between theplug means and the casing. This is especially important when the plugmeans is being expelled from the casing. The plug means should not, ofcourse, allow a sudden inrush of water towards the composition to occurwhen it is being expelled.

Advantageously, at least a part of the plug means is formed of felt orlike cloth material; alternatively, at least a part of the plug meansmay be formed of expanded polystyrene, preferably of low density. Thesaid part is preferably the portion of the plug means adjacent to thewall of the casing.

Advantageously, the plug means includes a plate member of cork orcard-board which is in contact with the surface of the composition andin close fit with the wall of the casing. It has been discovered thatthis serves to prevent water extinguishing combustion of the compositionwhen only part of the surface of the composition has been ignited.Preferably, the composition is arranged to be ignited, in operation,through a recess formed in the edge of the plate member, or through anaperture formed in the plate member. Preferably, a mass of ignitingmaterial is formed in the aperture or recess.

Advantageously, the igniting means includes a fuse to impart a delaybetween operating the igniting means and the ignition of thecomposition. This makes it possible for the device to be fired underwater and yet for the signal composition to commence combustion onlyafter the casing containing the composition has reached the surface. Alength of conventional Bickford (or safety) fuse may be employed.

Advantageously, the casing is contained in a watertight container, atpart of the water-tight container being arranged to be removable orrupturable in response to the gases of combustion generated to allowegress of the combustion products. With such an arrangement, a signaldevice may be carried under water for relatively long periods withoutfear of prejudicing the effectiveness of the device in operation.Preferably, the igniting means is electrically operated and is containedwithin the water-tight container, and the electric impulse to operate itis applied between two points on the outside of the water-tightcontainer. Such an ar rangement of igniting means is very reliable.Preferably, the plug means includes a number of members formed of felt,which are arranged with their axes parallel to the axis of the casing,and which are each in close fit with the wall of the casing.

Advantageously, the open end of the casing is provided with removableclosure means, thereby obviating the need for a separate water-tightcontainer to house the casing. if the igniting means includes a slowburning fuse, this (the fuse) may then extend substantially parallel tothe axis of the casing, and the plug means may then include a number offelt washers which each make a close fit with the fuse and with thecasing. The use of such felt washers has the advantage that thepossibility ofa frame from the priming on the fuse igniting the signalcomposition prematurely is reduced. The fuse will generally comprise athin train of gunpowder covered by a layer of textile or like material.Only the actual gunpowder will burn in operation, leaving the casing, sothat combustion gases passing down the centre of the fuse with besufficient to prevent water reaching the composition.

Preferably, the igniting means is arranged to be operated in response toa movement of the closure means relative to the casing which is suchthat the closure means is not removed from the casing. Such a device maybe operated without actually disengaging the closure means from thecasing, so that if the device is operated under water, the closure meanswill remain in engagement with the casing for at least a part of thepassage of the device towards the surface. This both prevents any waterentering the casing and provides additional buoyancy for the device. Theclosure means will be removed in due course by the pressure of thecombustion gases generated. If the user accidentally removes the closuremeans completely from the casing in operating the device, the ignitingmeans will nevertheless be operated before the closure means is removed,and for many designs of device and applications the device will functionnormally.

Preferably, the casing and the closure means are each tubular. As anadditional precaution against the ingress of water into the casing, asealing band of flexible material may be provided for surrounding thejoin between the casing and the closure means to provide a watertightseal, the arrangement being such that the join is surrounded by the bandboth before and after the movement of the closure means that operatesthe igniting means.

Alternatively, the igniting means may be arranged to be operated inresponse to removal of the closure means. This arrangement will onlygenerally be feasible in shallow water.

The igniting means advantageously comprises a percussion cap and astriker mechanism for striking the cap, the striker mechanism preferablybeing arranged to be operated by movement of the closure means relativeto the casing. The striker mechanism is preferably located towards theopen end of the casing, and a water-tight seal formed between the wallof the casing and the body of the striker mechanism. The plug means, inthis case, includes the body of the striker mechanism and the materialwhich forms the seal between the body of the striker mechanism and theinner wall of the easing. The location of the striker mechanism in thisway has the advantage that a region of reduced diameter, formed by theinterior of the body of the striker mechanism, is formed towards thelower end of the casing, and combustion gases passing out of the casingthrough this region of reduced diameter will tend to prevent or reducethe quantity of water entering the casing. This allows signal deviceswhich are operated in response to the removal of the closure means to beused at lower depths. Also, this provides an additional precautionagainst the ingress of water when devices in which the igniting means isoperated by moving the closure means relative to the casing but withoutdisengaging the closure means are mis-handled by the user accidentallyremoving the closure means when operating the device.

The signal composition is preferably a composition that produces asubstantial quantity of gas on combustion. The quantities of gasproduced by such compositions are such that the signal device is mademore buoyant in operation. The composition may be a smokeproducingcomposition or a flare-producing composition.

Two pyrotechnic signal devices, constructed in accordance with theinvention, will now be described in detail, by way of example, withreference to the accompanying drawings, in which:

FIG. l is an axial cross-section of the first signal device, and

FIG. 2 is an axial cross-section of the second signal device.

Like reference numerals are given to like parts in both drawings. Bothsignal devices are suitable for being operated and released from underwater.

Referring to FIG. I, the first signal device, which is a signal flaredevice, comprises a tubular metal casing l, which is closed at one endand open at the other, and a mass of flare composition 2 housed in thecasing adjacent to its closed end. A tubular closure member, indicatedgenerally by the reference numeral 3, which is in external sliding fitwith the casing ll, closes the open end of the casing, and a rubbersealing band 4 serves to make the join between the open end of theclousre member and the casing water-tight. The closure member 3 isformed on the outside with a number of circumferential ribs 5, whichenable it to be firmly gripped.

The ignition means of the signal flare device incorporates a percussioncap (not shown) and an un-cocked percussive striker mechanism, indicatedgenerally by the reference numeral 6, which is similar to the strikermechanism described in British Pat. application No. 26370/68. Thestriker mechanism 6 is operated by withdrawing a spring-loaded plunger 7from the casing 8 of the mechanism against the action of the spring.When the plunger 7 has been withdrawn far enough, it is released fromthe casing 8, and a member moves under the action of the spring andstrikes the percussion cap.

The plunger 7 is connected by means of a length of cord 9 to a screw it)formed in the base of the closure member 3. (In order to secure the cord9 to the screw 10 during manufacture of the device, the cord is passedthrough the hole in the base of the closure member 3, secured to thescrew 10, and the screw 10 is then screwed into the hole.) The casing 8of the striker mechanism is located in position at its upper end by ahollow cylindrical member 11 formed with projections 12 which engagewith recesses formed in the casing 8 of the striker mechanism. Thehollow cylindrical member 11 is located in position in the casing l bymeans of an annular sealing member 13, which fits tightly around thecylindrical member 11, and which is in close fit with the casing.Relative axial movement be tween the sealing member 13 and the casing 1is prevented by a circumferential rib 14 in the casing which engages arecess in the sealing member. The igniting mechanism is operated bymoving the closure member 3 away from the casing 1, the movement of theclosure member causing retraction of the plunger 7 from the casing 8.

The upper end of the hollow cylindrical member 11 is formed with aportion 15 of reduced diameter, through which passes a Bickford fuse 16.The fuse is secured in a ferrule 16a at its lower end. The fuse isiginited by the flame which emanates from the percussion cap when it isstruck.

The fuse to is surrounded by a number of felt washers 17 which, togetherwith the fuse itself, plug the casing between the open end and thecomposition 2, thereby tending to prevent or impede the passage of waterfrom the open end of the casing to the composition. The washers 117 arein close fit with both the fuse 16 and the wall of the casing 1. Thewashers 17 also serve to reduce or eliminate the possibility of a flamefrom the percussion cap or from priming on the fuse to directly strikingthe composition 2 and igniting it in advance of the main flame front.

The upper end of the fuse 16 is sealed by adhesive tape 18 to a capsuleof igniting material 19, which is directly in contact with a mass ofpriming composition 20 formed at the lower end of the mass of flarecomposition 2. Thus ignition of the fuse causes ignition of the flarecomposition 2. A cork washer 21, which surrounds the capsule of ignitingmaterial 1) and which is in contact both with the upper washer l7 andthe flare composition 2, allows combustion to proceed over that area ofthe composition which is in contact with the washer without interferencefrom any water which may have entered the signal device.

I The walls of the casing l are lined with an inhibiting layer in theform of a layer of paper 22, which prevents the heat from the combustionadversely affecting the casing and minimizes heat transfer down thesides of the composition 2 in advance of the flame front. It has beenfound that the layer of paper 22 also improves the reliability ofcombustion of the signal device.

The flare composition 2 is formed of the following components, the partsbeing by weight:

15 parts This composition will combust to produce a red flame.

in operation, when the device is operated under water, the closuremember 3 is moved in an axial direction away from the casing through adistance sufficient to cause the striker mechanism to operate. Thelength of the cord 9, and the distance which the plunger 7 must beretracted before it is released are such that this distance is notsufficient for the closure member 3 to be disengaged from the casing l;the sealing band protects the join between the casing and the closuremeans after the striker mechanism has been operated.

The closure member 3 remains in engagement with the casing l for atleast a part of the upward passage of the device towards the surface.Any water which may leak into the closure member 3 through the joinbetween the'closure member 3and the casing tends to be prevented fromentering the casing by virtue of the stream of combustion gasesemanating through the easing 8 of the striker mechanism 6 which forms aregion of reduced cross-sectional area and hence of increased gasvelocity.

When the fuse to has burned fully, and the composition 2 has beenproperly ignited, the closure member 3 is displaced from the casing 11by the combustion gases from the composition, and the igniting mechanism6 and the members 11 and 13 holding it in position are ejected from thecasing 1 by the combustion gases, together with the felt washers 17, thespent fuse l6 and cork disc 21. As the washers 17 are being ejected,they are compressed slightly axially by the gas pressure, and theresulting radial expansion, together with the absorption of water by thewashers, tends to prevent the sudden inrush of water impinging on, andextinguishing the combustion of the composition. When the washers 17have been expelled from the casing, the velocity of the combustion gasesleaving the end of the casing is sufficient to prevent the quantity ofwater entering the casing being great enough to extinguish thecomposition, and thus the composition is not extinguished even if thedevice has not reached the surface of the water by this time.

When the device reaches the surface, the free escape of combustionproducts from the composition 2 into the atmosphere then takes place.

if the user accidentally removes the closure member 3 from the casing lin operating the device, the combustion will not be extinguishedprovided the depth at which the device is operated is not too great,since the percussion cap will have been ignited before the closuremember 3 is completely removed, and the gases venting through the casing6 of the striker mechanism 8 will prevent the quantity of water thatenters being great enough to extinguish the combustion.

The second signal device is also a signal flare device and comprises acasing 1 housing signal composition 2 having the same composition as inthe first signal device.

The casing l is supported by means of foam plastic 23 in an uppercompartment 24 of a container indicated generally by the referencenumeral 25. The upper compartment 24 is water-tight, and is closed atthe top by a push-seal cap 26, which has an O-ring 27 extending aroundits circumference.

The signal device is electrically operated, and the electric impulse issupplied to two screws 28 and 29 via the lower compartment 301* of thecontainer 25 by means which are not shown. Wires pass from the screws 28and 29 to an electric fuse 31, which comprises a wire passing through acomposition which ignites when a suitable current passes through thewire. The electric fuse 31 ignites a delay fuse 32, which extendsthrough an aperture in the wall of the casing 1, and which in turnignites a mass of priming composition 33 which is in contact with thecomposition 2. Thus the composition is ignited by applying a suitableelectric impulse between the screws 28 and 29.

The priming composition 33 is surrounded by a cardboard washer 34 whichis in contact with the surface of the composition 2, and which performsthe same function as the cork washer 21 in the first device. The upperpart of the casing 1 is plugged by a number of felt discs 35. The feltdiscs 35 above the delay fuse 32 each make a good fit with the wall ofthe casing It When the device is operated and released from under water,an electric impulse is applied to the screws 28 and 29, and the electricfuse 31 ignites the delay fuse 32. The pressure rise in the compartment24 due to the combustion gases generated will, in due course, cause thepush-seal cap 26 to be displaced. The container 25 will have reached thesurface of the water by this time.

The felt discs 35 will prevent the quantity of water entering the casing1 from being large enough to extinguish the combustion and, when thecomposition 2 has ignited properly, the pressure of the combustion gasesgenerated will be such as to expel the discs 35 from the casing l. Thefree escape of combustion products from the casing 1 then takes place.

We claim:

1. A pyrotechnic device for underwater use comprising:

a. a casing having one open end,

b. a mass of signal composition in said casing,

c. signal composition igniting means, and

d. plug means plugging said casing between said signal composition andsaid open end of said casing to prevent or impede the passage of waterto said signal composition, said plug means being formed to permit theescape of combustion products when said device is initially ignited butto be expelled from said casing or be consumed by the combustion gaseswhen said combustion gases are generated at a higher rate,

and wherein:

e. said signal composition igniting means includes a fuse to impartdelay between the operation of said igniting means and the ignition ofsaid composition, said fuse extending substantially parallel to the axisof said casing, and

f. said plug means includes a number of felt washers, said washershaving a close fit with said fuse and with the inner surface of saidcasing.

2. A signal device according to claim 1, wherein:

g. removable closure means is provided for said open end of said casing,and

h. said igniting means is operable in response to a movement of saidclosure means relative to said casing which is such that said closuremeans is not removed from said casing.

3. A signal device according to claim 2, wherein:

i. said casing and said closure means are each tubular and in slidingfit with each other, and

j. a sealing band of flexible material surrounds the joint between saidcasing and said closure means to thereby provide a water-tight seal,said band surrounding said joint before and after said movement of saidclosure means that operates said igniting means.

4. A pyrotechnic signal device for underwater use comprising:

a. a casing having one open end,

b. a mass of signal composition in said casing,

c. Signal composition igniting means,

(1. a removable waterproof closure to prevent water entering the openend of the casing, said closure being readily removable in response tothe pressure of combustion gases generated when said device is ignited,

e. plug means plugging said casing between said signal composition andsaid open end of said casing to prevent or impede the passage of waterto said signal composition, and

f. at least a portion of said plug means being compressible and in tightfit with the wall of said casing to tend to retain said plug means insaid casing, said plug means being formed to permit the escape ofcombustion products when said device is initially ignited, whereby saidclosure but not said plug means becomes removed, but to be expelled fromsaid casing or be consumed by the combustion gases only when saidcombustion gases are generated at a higher rate, said compressibleportion of said plug means remaining in e. close fit with the wall ofsaid casing while being expelled from said casing.

5. A signal device as claimed in claim 4, wherein g. said signalcomposition igniting means includes a fuse,

h. said fuse extends through a passageway terminating adjacent thesurface of the composition, and

i. said compressible portion of said plug means comprises a number offelt discs between said signal composition and said open end of saidcasing, said felt discs being arranged with their axes parallel to theaxis of said casing and being in close fit with the wall of said casing.

6. A signal device as claimed in claim 5, wherein:

j. said passageway extends from adjacent the surface of said signalcomposition through said plug means.

7. A signal device as claimed in claim 5, wherein:

j. said passageway extends through said casing adja cent the surface ofsaid signal composition.

8. A signal device as claimed in claim 7, wherein:

k. said fuse is electrically ignited,

i. said device further comprises a water-tight container housing saidfuse and said casing, and

m. said container is closed by said waterproof closure.

9. A signal device as claimed in claim 4, wherein:

g. said plug means includes a plate-like member, said plate-like memberbeing maintained by said compressible portion of said plug means incontact with the surface of said composition to be ignited,

h. said plate-like member has an opening therein to permit ignition ofsaid composition therethrough,

i. said signal composition igniting means includes a fuse, and

j. said signal composition igniting means further includes a mass ofigniting material positioned adjacent an end of said fuse and adjacentsaid opening to thereby facilitate the spreading of combustion over thatarea of said signal composition with which said plate-like member is incontact.

10. A pyrotechnic signal device for underwater use comprising:

and wherein e. a portion of said plug means is compressible and has aclose fit with the wall of said casing while being expelled from saidcasing,

f. the open end of said casing is provided with removable closure means,

g. said igniting means comprises a percussion cap and a striker meansfor striking said cap, said striker means being operable to strike saidcap in response to a movement of said closure means relative to saidcasing,

h. said striker means being located toward said open end of said casingand displaceable therefrom with said plug, and forming a watertight sealbetween its body and the wall of said casing before such displacement,and

i. the body of said striker mechanism defining an outlet of reducedcross-sectional area before such displacement.

1. A pyrotechnic device for underwater use comprising: a. a casinghaving one open end, b. a mass of signal composition in said casing, c.signal compositioN igniting means, and d. plug means plugging saidcasing between said signal composition and said open end of said casingto prevent or impede the passage of water to said signal composition,said plug means being formed to permit the escape of combustion productswhen said device is initially ignited but to be expelled from saidcasing or be consumed by the combustion gases when said combustion gasesare generated at a higher rate, and wherein: e. said signal compositionigniting means includes a fuse to impart delay between the operation ofsaid igniting means and the ignition of said composition, said fuseextending substantially parallel to the axis of said casing, and f. saidplug means includes a number of felt washers, said washers having aclose fit with said fuse and with the inner surface of said casing.
 2. Asignal device according to claim 1, wherein: g. removable closure meansis provided for said open end of said casing, and h. said igniting meansis operable in response to a movement of said closure means relative tosaid casing which is such that said closure means is not removed fromsaid casing.
 3. A signal device according to claim 2, wherein: i. saidcasing and said closure means are each tubular and in sliding fit witheach other, and j. a sealing band of flexible material surrounds thejoint between said casing and said closure means to thereby provide awater-tight seal, said band surrounding said joint before and after saidmovement of said closure means that operates said igniting means.
 4. Apyrotechnic signal device for underwater use comprising: a. a casinghaving one open end, b. a mass of signal composition in said casing, c.signal composition igniting means, d. a removable waterproof closure toprevent water entering the open end of the casing, said closure beingreadily removable in response to the pressure of combustion gasesgenerated when said device is ignited, e. plug means plugging saidcasing between said signal composition and said open end of said casingto prevent or impede the passage of water to said signal composition,and f. at least a portion of said plug means being compressible and intight fit with the wall of said casing to tend to retain said plug meansin said casing, said plug means being formed to permit the escape ofcombustion products when said device is initially ignited, whereby saidclosure but not said plug means becomes removed, but to be expelled fromsaid casing or be consumed by the combustion gases only when saidcombustion gases are generated at a higher rate, said compressibleportion of said plug means remaining in e. close fit with the wall ofsaid casing while being expelled from said casing.
 5. A signal device asclaimed in claim 4, wherein g. said signal composition igniting meansincludes a fuse, h. said fuse extends through a passageway terminatingadjacent the surface of the composition, and i. said compressibleportion of said plug means comprises a number of felt discs between saidsignal composition and said open end of said casing, said felt discsbeing arranged with their axes parallel to the axis of said casing andbeing in close fit with the wall of said casing.
 6. A signal device asclaimed in claim 5, wherein: j. said passageway extends from adjacentthe surface of said signal composition through said plug means.
 7. Asignal device as claimed in claim 5, wherein: j. said passageway extendsthrough said casing adjacent the surface of said signal composition. 8.A signal device as claimed in claim 7, wherein: k. said fuse iselectrically ignited, l. said device further comprises a water-tightcontainer housing said fuse and said casing, and m. said container isclosed by said waterproof closure.
 9. A signal device as claimed inclaim 4, wherein: g. said plug means includes a plate-like member, saidplate-like member being maintained by Said compressible portion of saidplug means in contact with the surface of said composition to beignited, h. said plate-like member has an opening therein to permitignition of said composition therethrough, i. said signal compositionigniting means includes a fuse, and j. said signal composition ignitingmeans further includes a mass of igniting material positioned adjacentan end of said fuse and adjacent said opening to thereby facilitate thespreading of combustion over that area of said signal composition withwhich said plate-like member is in contact.
 10. A pyrotechnic signaldevice for underwater use comprising: a. a casing having one open end,b. a mass of signal composition in said casing, c. signal compositionigniting means, and d. plug means plugging said casing between saidsignal composition and said open end of said casing to prevent or impedethe passage of water to said signal composition, said plug means beingformed to permit the escape of combustion products when said device isinitially ignited but to be expelled from said casing to be consumed bythe combustion gases when said combustion gases are generated at ahigher rate, and wherein e. a portion of said plug means is compressibleand has a close fit with the wall of said casing while being expelledfrom said casing, f. the open end of said casing is provided withremovable closure means, g. said igniting means comprises a percussioncap and a striker means for striking said cap, said striker means beingoperable to strike said cap in response to a movement of said closuremeans relative to said casing, h. said striker means being locatedtoward said open end of said casing and displaceable therefrom with saidplug, and forming a watertight seal between its body and the wall ofsaid casing before such displacement, and i. the body of said strikermechanism defining an outlet of reduced cross-sectional area before suchdisplacement.